The Large Hadron Collider, a 17-mile-round atom-smasher on the French-Swiss border, has been 14 years and several billion dollars in the making. The machine is designed to rev up opposing beams of particles to nearly the speed of light and smash them together. The debris, observed with detectors, including ATLAS shown here, will help scientists probe some of the deepest questions in science: What was the universe like moments after the Big Bang? What's the nature of dark matter? Why do only some particles have mass? Are there more dimensions than space and time? A few scientists are even concerned the collisions will create tiny black holes that destroy the earth. Click the "Next" arrow above to learn about six more atom-smashers that were at the cutting edge of science in their day.

1930: The first particle accelerator

Courtesy of Lawrence Berkeley National Laboratory

To understand the innards of atomic nuclei, scientists first need to ramp up particles to high enough energy to smash them apart. In 1930, a young scientist in California named Ernest Lawrence, inspired by a sketch of a hypothetical accelerator in a research journal, built the contraption shown here to do just that. Cobbled together with wire, glass, sealing wax and bronze, it bumps up particles between electrodes, whirling them around in a spiral. By keeping them in a circular route, their energy could be ratcheted up bit by bit. The accelerator, called a cyclotron, worked. Lawrence applied 2,000 volts of electricity and boosted hydrogen electron molecules up to 80,000 volts. It opened the door to particle physics and the era known as "big science," employing hundreds of people to tackle some of science's weightiest problems.

In 1966, electrons and positrons began zipping down the 2-mile-long Stanford Linear Accelerator, the longest atom-smasher of its type in the world. Shown here from above, the accelerator shoots the particles at near light speed down a mostly copper tube and into various targets, where they smash up into many more particles to be observed. The experiments have yielded three Nobel-winning discoveries: 1974 for the charm quark, a type of matter particle; 1990 for the quark structure inside protons and neutrons; and 1995 for the tau lepton. In addition to discovering new particles, the accelerator contributes to science in other ways. For example, X-ray beams generated by the accelerator were used in 2005 to decipher hidden writings of the ancient Greek mathematician Archimedes.

1974: TRIUMF, the triumphant cyclotron

TRIUMF

The world's biggest cyclotron, called TRIUMF, is located in the suburbs of Vancouver in Canada. A 59-foot-diameter magnet spins protons up to three-quarters the speed of light and then spits them out on a path to one of several destinations. There, they are smashed into ever-smaller particles for a host of experiments. At one destination called the Isotope Separator and Accelerator, scientists are learning about the earliest exploding stars that gave rise to the elements we see on earth today. Other experiments use the proton beam to treat eye cancer and study diseases such as Parkinson's. In this photo, a technician is dwarfed inside the cyclotron during a maintenance session.

1983: Tevatron, a champion in twilight

Fermilab

The Tevatron, which went into action in 1983, preceded the Large Hadron Collider as the champion of particle accelerators. The 4-mile-round track sits underground amid cow pastures in suburban Chicago and smashes beams of protons and antiprotons together at energies up to 1.8 trillion electron volts, or 1.8 TeV. The LHC is expected to reach a much higher energy of 14 TeV — sufficient, scientists believe, to find the elusive Higgs boson, a particle thought to give other particles mass. But even as the LHC was still under construction, the scientific rumor mill was buzzing with word that "something interesting" had shown up in one of the Tevatron's detectors. Could it be the Higgs boson? The Tevatron's budget was extended to allow operation into 2009, maybe beyond, to find out.

The Relativistic Heavy Ion Collider (RHIC, pronounced "rick") on Long Island in New York smashes beams of gold ions together in pursuit of a mysterious dense state of matter called a quark-gluon plasma that existed a millionth of a second after the Big Bang. The beam bursts are sped up to 99.95 percent the speed of light and injected into a 2.4-mile racetrack, shown here, in opposite directions. Where the bursts collide, scientists look for the extremely short-lived plasma, thought to exist for no longer than a billionth of a trillionth of a second. Scientists announced in March 2005 that they may have succeeded, but the plasma appears to be a nearly "perfect" liquid rather than a gas. Collisions are ongoing.

Future: The International Linear Collider?

Courtesy of International Linear Collider

The Large Hadron Collider is expected to be a smashing success on the road to new discoveries, but how will physicists make sense of what they find? The International Linear Collider, shown here in an artistic rendering, just might do the trick. It's envisioned as a sort of scalpel to pick apart the high-energy particles chiseled off by the LHC. Preliminary designs are for two linear accelerators to hurl electrons and their anti-particles, called positrons, toward each other at nearly the speed of light. No site has been selected for the approximately 22-mile-long atom-smasher, and budget cuts threaten to hobble its progress — leaving some particle physicists wondering whether there will be a frontier beyond the LHC.